HIV-2 infection is rare in Australia and antibodies to HIV-2 proteins in most sera from people with HIV-2 infection will cross-react with HIV-1 proteins in Western Blot assays. Specific HIV-2 Western Blot assays can be used to confirm HIV-2 infection and distinguish it from HIV-1. However, the cross-reactivity between HIV-1 and HIV 2 is often significant making it difficult to conclusively differentiate the infections. There have been reported cases of misdiagnosis of HIV-2 in cases of HIV-1 infection due to this cross-reactivity.